Controls whether CMS displays success and informational messages
    on the default output device. By default, if the command executes
    successfully, CMS displays a success message. If you specify
    /NOLOG, success and informational messages are suppressed. Any
    warning, error, or fatal error messages are displayed regardless
    of whether /LOG or /NOLOG is specified.
    Use MODIFY LIBRARY to change this attribute on an existing library.